Milling machines

ABSTRACT

Milling apparatus for milling fluent solids or suspensions wherein a mixing member is drivingly rotatable in a rotatable bowl containing the fluent solid or suspension and milling element and the drive to the mixing member is by a shaft extending through the base of the bowl for compactness of the apparatus. In a preferred case the mixing member is carried on the lower end of a supporting sleeve connected at its top and to said shaft and a sealing sleeve means connected to the base of the bowl lies between the supporting sleeve and shaft to seal the shaft from the container contents in that the top of the sealing sleeve means lies above the normal level of material in the bowl. A single drive unit and transmission is used to drive both the mixing member and, selectively, the bowl (depending upon the direction of rotation of the drive unit).

United States Patent 1191 Morley 14 1 Nov. 19, 1974 MILLING MACHINES Prima Examiner-Granville Y. Custer Jr. l E W [75] Inventor Douglas Morley Ha "gland Assistant Examiner-Howard N. Goldberg 1 Assigneer g Limited, i Attorney, Agent, or Firm-Wolf, Greenfield & Sacks Yorkshire, England 22 Filed: May 21, 1973 ABSTRACT [21] Appl NO: 362,227 Milling apparatus for milling fluent solids or suspensions wherein a mixing member is drivingly rotatable in a rotatable bowl containing the fluent solid or sus- U.S. pension and element and the drive to the mix- 241/172, 241/2821 ing member is by a shaft extending through the base of It. Cl. the bow] for compactness of the apparatus In a pre- Fleld Of Search 65-66, fen-ed ease the mixing member is carried on the lower end of a supporting sleeve connected at its top and to said shaft and a sealing sleeve means connected to the References Cited base of the bowl lies between the supporting sleeve UNITED STATES PATENTS and shaft to seal the shaft from the container contents 2,246,054 6/1941 Marty 24l/282.l x ht that the P of the Sealing Sleeve means lies above 2,894,551 7 1959 Otto 241 /282.1 x the normal level of material in the howl- A Single drive 3,233,835 2/1966 Sevin et aL. 241/171 X unit and transmission is used to drive both the mixing 3,350,280 10/1967 West 214/66 X member and, selectively, the bowl (depending upon 3,352,501 67 Krumholz 241/74 the direction of rotation of the drive unit). 3,545,687 l2/l970 Mosby 211/172 X 3,682,399 8/1972 Kaspar et al 241/172 x 5 Clalms, 2 Drawmg Figures i 1 I" t MILLING MACHINES FIELD OF INVENTION This invention relates to milling apparatus of the type which comprises a bowl or container in which is located a rotatable mixing member; the bowl or container in use includes a plurality of milling elements such as small beads, blocks, plates, or the like which may be of any suitable material such as glass, plastics material, which elements upon rotation of the mixing member perform by relative movements, the function of milling and dispersing into more finely divided form fluent solid materials and dispersions placed in the bowl to be so milled.

Milling apparatus of the aforesaid type has many uses in industry, such uses including the milling of paint pigments with solvent, pharmaceutical substances, printing inks, toothpaste and flour.

DISCUSSION OF PRIOR ART In the prior art milling apparatus of the aforesaid type the bowl is adapted to be driven for the centrifugal discharge of the milled substance after the milling operation, the drive for the bowl being independent of the drive for the mixing member. Because of this independence of bowl and mixing member drives, the drive connection to the mixing member is via a shaft which extends down into the bowl from above, the mixing member being mounted on the lower end of the said shaft.

By virtue of the necessary overhead assembly to support the shaft, this known machine is much larger than it is felt it need be; it is therefore more expensive, takes up more room and is more difficult to transport than it need be.

It is a principal object of the invention to provide a milling apparatus of the aforesaid type which although of the same general capacity of the prior art apparatus discussed above, may be of smaller overall dimensions and cost.

It is a further object of the present invention to provide a milling apparatus of the type to which the invention relates wherein a common, single prime mover is used for the driving of the bowl and the mixing member.

Another object is to provide in the apparatus a mounting for the mixing member whereby the sealing of the rotary assembly of the mixing member relative to the bowl may be facilitated.

It is furthermore an object of the present invention to provide a coupling arrangement for the drive connections to the bowl and mixing member whereby the single prime mover may be selectively connected to the bowl.

SUMMARY OF THE INVENTION According to the proposal of our invention, a milling apparatus of the type aforesaid is constructed so that the drive to the rotatable mixing member is through the base of the bowl. By this means, the height of the appa ratus as compared with the known type is much reduced and moreover, the filling of the bowl with the milling elements and the substance(s) to be milled is easier because of the absence of a mixing member overhead drive shaft.

Moreover, by a one way clutch arrangement, it is possible to use the same drive unit or motor for the mixing member and the bowl, where the bowl is of the rotatable centrifugal discharge type. In some cases however, the bowl may remain stationary throughout the operation with the milled substance being removed by, for example, a pump.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional elevation of a part of milling apparatus according to a first embodiment of the invention; and

FIG. 2 is a sectional elevation of part of milling apparatus according to a second embodiment of the present invention.

Referring to the drawings, and firstly to the embodiment shown in FIG. 1, the bowl 10 is of inverted frustoconical form and is made up of a base plate casting 12 and a metal plate wall 14.

Connected to the top of wall 14 is an annular filter plate 16 having a central filling aperture 18, the plate 16 being provided with a plurality of filter bores 20.

Located above the plate 16 and generally in line with wall 14 is a cylindrical filter screen 22 having radial bores 24 therein. A filter screen retainer ring 26 is connected to the top edge of screen 22 via a flange 28 of the screen.

The bowl 10 is contained within a stationary casing 30, provided internally with cooling pipes 32 through which cooling medium is circulated to keep cool the substance being milled.

An L-sectioned ring 34 welded on the outside of casing 30, together with casing 30, defines an annular collection chamber 36 and a hood 38, which is split into two separably removable parts, rests on the top peripheral edge of ring 34 and covers the open end of bowl 10. The hood 38 carries a feed chute 40 which is of inverted, frustoconical form and which leads into the interior of the bowl 10 by projecting through aperture 18.

The base plate 12 of bowl 10 is centrally bored and is secured to a drive sleeve 42 concentric with the axis of the bore in plate 12. The sleeve 42 is mounted for rotation, through bearing 43, on a frame 44 located under the bowl l0 and on which the casing 30 is mounted. Within the sleeve 42 is a drive shaft 46. This shaft 46 projects out of the end of sleeve 42 at the bottom end thereof and out through the base plate 12 and into the interior of the bowl 10 at the top end thereof. The shaft 46 is rotatably mounted in bearings 48, 50 respectively carried by the sleeve 42 and frame 44.

At the lower end the drive shaft is drivingly connected to a reversible prime mover, such as a reversible hydraulic or electric motor 45, through an infinitely variable ratio belt and pulley drive of which the automatically expansible and contractible pulley as shown at 52 in FIG. 1 and the belt at 53. The other pulley 47 is driven by the prime mover 45 and is connected in conventional manner to means for expanding or contracting same to vary the speed ratio between the pulleys. By this drive means, the shaft 46 can be rotated at will in either direction and at any speed within the ratio range of the pulleys. At the top end, the shaft 46 has secured thereto a mixing member in the form of an agitator disc 54. This disc 54 may be of known configuration with a plurality of holes 56 therein and a plurality of deflecting and agitating vanes 58.

Between the plate 12 and the sleeve 42 there is one way clutch 60, the purpose of which is to ensure that when the shaft 46 is rotating in one direction there is no drive to the bowl 10, whilst rotation of the shaft 46 in the other direction causes rotation of the bowl l and agitator disc 54 together. The sleeve 42 may carry a brake drum to which a brake pad is applied positively to brake the bowl when the shaft 46 is rotating in the direction causing clutch 60 to free wheel. Sealing disc 66 and a deflector ring 68 prevent flow of material from bowl 10 to bearings 43, 48, 50 and one way clutch 60. The deflector ring 68 is located in a cavity 70 in base 12, said cavity 70 being located above the clutch 60. The deflector ring 68 is fast with shaft 46 and rotates therewith. Thus, when shaft 46 rotates, if any liquid medium seeps past seals 66, it is deflected outwardly in cavity 70 and flows away from the clutch 60 through a discharge passage 72.

In operation of the FIG. 1 embodiment, the bowl 10 is approximately half full of small (3 mm. dia) glass beads to which is added the substance to be milled. In the case of milling paint, such substance may be the paint pigment; a solvent would also be added. The shaft 46 and agitator 54 are driven in the direction in which clutch 60 freewheels, the bowl 10 being psotively braked by the brake pad. During this time the beads are agitated and churned whereby a multiplicity of relative movements take place within the mass of beads, and as is well known, such relative movements result in a grinding or milling of the paint pigment to finely divided form. When milling has been completed, the shaft 46 is driven in reverse after the brake pad 64 is released from drum 62, and by centrifugal action the fluent mass, beads and milled substance starts to move radially outwards and then up the inside of wall 14. Filter plate 16 prevents only the beads from passing beyond the plate 16, whilst filter screen 22 removes smaller foreign particules, the remaining finely dispersed substance passing through screen 22 and into annular chamber 36 from a discharge outlet from which it is collected.

In the embodiment of which only part is shown in sectional elevation in FIG. 2, the need for the deflector plate 68 is obviated by the manner of mounting the agitator plate 54. Otherwise the construction of the apparatus is identical with that described in relation to FIG. 1 and reference is made to such description for particular details.

In the arrangement of FIG. 2 the shaft 46 is extended upwardly so that the top end thereof is located at a level which is normally above the level 88 to which the bowl is filled in operation.

Surrounding that portion of shaft 46 which extends upwardly in the bowl is a sealing sleeve 80 which is sealingly and rigidly connected to the base 12 of the bowl, said sleeve 80 carrying bearings 82 and 84 in which the shaft 46 is journalled.

The agitator 54 is carried by a supporting sleeve 86 which surrounds sleeve 80 and which is connected to the top end of shaft 46 projecting beyond the top end of sleeve 80 as shown clearly in the drawing.

The normal level to which the bowl is filled is indicated in FIG. 2 by reference numeral 88 and it will be seen therefore that it is not possible for the liquid medium in the bowl to leak to the clutch 60 because the level 88 will not normally be higher than the top of the sealing sleeve 80. As a precaution however there is a sealing ring 90 between the bore end of the supporting sleeve 86 and'the sealing sleeve 80. This sealing ring 90 also serves as a support bearing for the lower end of the sleeve 86 to prevent this sleeve 86 and the agitator plate 54 from deflecting excessively when rotated.

It will be appreciated that the sealing sleeve rotates only when the bowl and agitator 54 are rotated together as described previously and during such rotation the sealing problem is much reduced.

The apparatus described with reference to FIG. 1 and FIG. 2 are compact and of smaller overall dimensions as compared with the known machine of comparable capacity and a saving in cost is obtained because only one prime mover is required, although this invention applies in cases where separate drives for the bowl and agitator are used.

It is to be appreciated that the embodiments of the invention described and illustrated are given by way of example only and that modifications may be made thereto without departing from the scope of the invention as defined by the appended claims.

I claim:

1. Milling apparatus comprising a rotatable bowl which has a base and side wall means and which is for holding a quantity of fluent material to be milled and a plurality of milling elements, a rotatable mixing member mounted in the bowl, a drive shaft means which extends through the base of the bowl and which is drivingly connected to the mixing member, a prime mover, and transmission means operatively coupling the prime mover and the drive shaft means and the prime mover and the bowl whereby the mixing member selectively can be driven independently of the bowl for the milling operation, and the bowl can be rotated by the prime mover to centrifugally discharge the milled substance from the top of the bowl.

2. Milling apparatus according to claim 1, wherein the prime mover is reversible and the transmission means include a drive connection between the prime mover and the drive shaft means and a one way clutch arrangement connected between the drive shaft means and the bowl so that in one direction of drive of said prime mover, the mixing member and bowl are drivingly connected for rotation together, whereas in the other direction of drive of the prime mover only the mixing member is driven, the one way clutch arrangement serving to prevent transmission of drive to the bowl.

3. Milling apparatus according to claim 2, wherein the clutch arrangement is sealed from the interior of the bowl and there is a deflector plate located above the one way clutch arrangement which is connected to rotate with the mixing member to deflect any milled substance which leaks past the sealing from reaching the clutch.

4. Milling apparatus comprising a rotatable bowl which has a base and side wall means and which is for holding a quantity of fluent material to be milled and a plurality of milling elements, a rotatable mixing member mounted in the bowl, a drive shaft means which extends through the base of the bowl and which is drivingly connected to the mixing member, a supporting sleeve surrounding a portion of the shaft means which extends upwardly into said bowl, the supporting sleeve being attached to the top end of the shaft means, a sealing sleeve means which also surrounds the said portion of the shaft means, the sealing sleeve means being disposed between the supporting sleeve and the shaft means, and forming a seal with the bowl base where the shaft passes therethrough, the top end of the sealing sleeve means being located above the normal level to which the bowl will be filled in use, a prime mover, and transmission means operatively coupling the prime mover and the drive shaft means and the prime mover and the bowl whereby the mixing member selectively can be driven independently of the bowl for the milling operation, and the bowl can be rotated by the prime mover to centrifugally discharge the milled substance from the top of the bowl.

5. Milling apparatus according to claim 4 wherein the bowl. 

1. Milling apparatus comprising a rotatable bowl which has a base and side wall means and which is for holding a quantity of fluent material to be milled and a plurality of milling elements, a rotatable mixing member mounted in the bowl, a drive shaft means which extends through the base of the bowl and which is drivingly connected to the mixing member, a prime mover, and transmission means operatively coupling the prime mover and the drive shaft means and the prime mover and the bowl whereby the mixing member selectively can be driven independently of the bowl for the milling operation, and the bowl can be rotated by the prime mover to centrifugally discharge the milled substance from the top of the bowl.
 2. Milling apparatus according to claim 1, wherein the prime mover is reversible and the transmission means include a drive connection between the prime mover and the drive shaft means and a one way clutch arrangement connected between the drive shaft means and the bowl so that in one direction of drive of said prime mover, the mixing member and bowl are drivingly connected for rotation together, whereas in the other direction of drive of the prime mover only the mixing member is driven, the one way clutch arrangement serving to prevent transmission of drive to the bowl.
 3. Milling apparatus according to claim 2, wherein the clutch arrangement is sealed from the interior of the bowl and there is a deflector plate located above the one way clutch arrangement which is connected to rotate with the mixing member to deflect any milled substance which leaks past the sealing from reaching the clutch.
 4. Milling apparatus comprising a rotatable bowl which has a base and side wall means and which is for holding a quantity of fluent material to be milled and a plurality of milling elements, a rotatable mixing member mounted in the bowl, a drive shaft means which extends through the base of the bowl and which is drivingly connected to the mixing member, a supporting sleeve surrounding a portion of the shaft means which extends upwardly into said bowl, the supporting sleeve being attached to the top end of the shaft means, a sealing sleeve means which also surrounds the said portion of the shaft means, the sealing sleeve means being disposed between the supporting sleeve and the shaft means, and forming a seal with the bowl base where the shaft passes therethrough, the top end of the sealing sleeve means being located above the normal level to which the bowl will be filled in use, a prime mover, and transmission means operatively coupling the prime mover and the drive shaft means and the prime mover and the bowl whereby the mixing member selectively can be driven independently of the bowl for the milling operation, and the bowl can be rotated by the prime mover to centrifugally discharge the milled substance from the top of the bowl.
 5. Milling apparatus according to claim 4 wherein the prime mover is reversible and the transmission means include a drive connection between the prime mover and the drive shaft means and a one way clutch arrangement connected between the drive shaft means and the bowl so that in one direction of drive of the prime mover, the mixing member and bowl are drivingly connected for rotation together, whereas in the other direction of drive of the prime mover only the mixing member is driven, the one way clutch arrangement serving to prevent transmission of drive to the bowl. 